drivers/rc/crsf_rc: update standalone driver for CRSF and direct support for lq/rssi (#20084)

Co-authored-by: Chris Seto <chris1seto@gmail.com>
2026-10-24 04:23:33 +08:00 · 2022-09-23 19:19:25 -04:00
parent 86cddc6a52
commit 77fdce9f3c
20 changed files with 1135 additions and 793 deletions
@@ -0,0 +1,352 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2022 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+* @file CrsfParser.cpp
+*
+* Parser for incoming CRSF packets
+*
+* @author Chris Seto <chris1seto@gmail.com>
+*/
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+#include "QueueBuffer.hpp"
+#include "CrsfParser.hpp"
+#include "Crc8.hpp"
+
+#define CRSF_CHANNEL_VALUE_MIN  172
+#define CRSF_CHANNEL_VALUE_MAX  1811
+#define CRSF_CHANNEL_VALUE_SPAN (CRSF_CHANNEL_VALUE_MAX - CRSF_CHANNEL_VALUE_MIN)
+#define CRSF_MAX_PACKET_LEN 64
+#define CRSF_HEADER 0xc8
+
+enum CRSF_PAYLOAD_SIZE {
+	CRSF_PAYLOAD_SIZE_GPS = 15,
+	CRSF_PAYLOAD_SIZE_BATTERY = 8,
+	CRSF_PAYLOAD_SIZE_LINK_STATISTICS = 10,
+	CRSF_PAYLOAD_SIZE_RC_CHANNELS = 22,
+	CRSF_PAYLOAD_SIZE_ATTITUDE = 6,
+};
+
+enum CRSF_PACKET_TYPE {
+	CRSF_PACKET_TYPE_GPS = 0x02,
+	CRSF_PACKET_TYPE_BATTERY_SENSOR = 0x08,
+	CRSF_PACKET_TYPE_LINK_STATISTICS = 0x14,
+	CRSF_PACKET_TYPE_OPENTX_SYNC = 0x10,
+	CRSF_PACKET_TYPE_RADIO_ID = 0x3A,
+	CRSF_PACKET_TYPE_RC_CHANNELS_PACKED = 0x16,
+	CRSF_PACKET_TYPE_ATTITUDE = 0x1E,
+	CRSF_PACKET_TYPE_FLIGHT_MODE = 0x21,
+	// Extended Header Frames, range: 0x28 to 0x96
+	CRSF_PACKET_TYPE_DEVICE_PING = 0x28,
+	CRSF_PACKET_TYPE_DEVICE_INFO = 0x29,
+	CRSF_PACKET_TYPE_PARAMETER_SETTINGS_ENTRY = 0x2B,
+	CRSF_PACKET_TYPE_PARAMETER_READ = 0x2C,
+	CRSF_PACKET_TYPE_PARAMETER_WRITE = 0x2D,
+	CRSF_PACKET_TYPE_COMMAND = 0x32,
+	// MSP commands
+	CRSF_PACKET_TYPE_MSP_REQ = 0x7A,   // response request using msp sequence as command
+	CRSF_PACKET_TYPE_MSP_RESP = 0x7B,  // reply with 58 byte chunked binary
+	CRSF_PACKET_TYPE_MSP_WRITE = 0x7C, // write with 8 byte chunked binary (OpenTX outbound telemetry buffer limit)
+};
+
+enum CRSF_ADDRESS {
+	CRSF_ADDRESS_BROADCAST = 0x00,
+	CRSF_ADDRESS_USB = 0x10,
+	CRSF_ADDRESS_TBS_CORE_PNP_PRO = 0x80,
+	CRSF_ADDRESS_RESERVED1 = 0x8A,
+	CRSF_ADDRESS_CURRENT_SENSOR = 0xC0,
+	CRSF_ADDRESS_GPS = 0xC2,
+	CRSF_ADDRESS_TBS_BLACKBOX = 0xC4,
+	CRSF_ADDRESS_FLIGHT_CONTROLLER = 0xC8,
+	CRSF_ADDRESS_RESERVED2 = 0xCA,
+	CRSF_ADDRESS_RACE_TAG = 0xCC,
+	CRSF_ADDRESS_RADIO_TRANSMITTER = 0xEA,
+	CRSF_ADDRESS_CRSF_RECEIVER = 0xEC,
+	CRSF_ADDRESS_CRSF_TRANSMITTER = 0xEE,
+};
+
+#define HEADER_SIZE           1
+#define PACKET_SIZE_SIZE      1
+#define PACKET_TYPE_SIZE      1
+#define PACKET_SIZE_TYPE_SIZE 2
+#define CRC_SIZE              1
+
+enum PARSER_STATE {
+	PARSER_STATE_HEADER,
+	PARSER_STATE_SIZE_TYPE,
+	PARSER_STATE_PAYLOAD,
+	PARSER_STATE_CRC,
+};
+
+typedef struct {
+	uint8_t packet_type;
+	uint32_t packet_size;
+	bool (*processor)(const uint8_t *data, const uint32_t size, CrsfPacket_t *const new_packet);
+} CrsfPacketDescriptor_t;
+
+static bool ProcessChannelData(const uint8_t *data, const uint32_t size, CrsfPacket_t *const new_packet);
+static bool ProcessLinkStatistics(const uint8_t *data, const uint32_t size, CrsfPacket_t *const new_packet);
+
+#define CRSF_PACKET_DESCRIPTOR_COUNT  2
+static const CrsfPacketDescriptor_t crsf_packet_descriptors[CRSF_PACKET_DESCRIPTOR_COUNT] = {
+	{CRSF_PACKET_TYPE_RC_CHANNELS_PACKED, CRSF_PAYLOAD_SIZE_RC_CHANNELS, ProcessChannelData},
+	{CRSF_PACKET_TYPE_LINK_STATISTICS, CRSF_PAYLOAD_SIZE_LINK_STATISTICS, ProcessLinkStatistics},
+};
+
+static enum PARSER_STATE parser_state = PARSER_STATE_HEADER;
+static uint32_t working_index = 0;
+static uint32_t working_segment_size = HEADER_SIZE;
+
+#define RX_QUEUE_BUFFER_SIZE 200
+static QueueBuffer_t rx_queue;
+static uint8_t rx_queue_buffer[RX_QUEUE_BUFFER_SIZE];
+static uint8_t process_buffer[CRSF_MAX_PACKET_LEN];
+static CrsfPacketDescriptor_t *working_descriptor = NULL;
+
+static CrsfPacketDescriptor_t *FindCrsfDescriptor(const enum CRSF_PACKET_TYPE packet_type);
+
+void CrsfParser_Init(void)
+{
+	QueueBuffer_Init(&rx_queue, rx_queue_buffer, RX_QUEUE_BUFFER_SIZE);
+}
+
+static float ConstrainF(const float x, const float min, const float max)
+{
+	if (x < min) {
+		return min;
+
+	} else if (x > max) {
+		return max;
+	}
+
+	return x;
+}
+
+static float MapF(const float x, const float in_min, const float in_max, const float out_min, const float out_max)
+{
+	return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
+}
+
+static bool ProcessChannelData(const uint8_t *data, const uint32_t size, CrsfPacket_t *const new_packet)
+{
+	uint32_t raw_channels[CRSF_CHANNEL_COUNT];
+	uint32_t i;
+
+	new_packet->message_type = CRSF_MESSAGE_TYPE_RC_CHANNELS;
+
+	// Decode channel data
+	raw_channels[0] = (data[0] | data[1] << 8) & 0x07FF;
+	raw_channels[1] = (data[1]  >> 3 | data[2] << 5) & 0x07FF;
+	raw_channels[2] = (data[2] >> 6 | data[3] << 2 | data[4] << 10) & 0x07FF;
+	raw_channels[3] = (data[4] >> 1 | data[5] << 7) & 0x07FF;
+	raw_channels[4] = (data[5] >> 4 | data[6] << 4) & 0x07FF;
+	raw_channels[5] = (data[6] >> 7 | data[7] << 1 | data[8] << 9) & 0x07FF;
+	raw_channels[6] = (data[8] >> 2 | data[9] << 6) & 0x07FF;
+	raw_channels[7] = (data[9] >> 5 | data[10] << 3) & 0x07FF;
+	raw_channels[8] = (data[11] | data[12] << 8) & 0x07FF;
+	raw_channels[9] = (data[12] >> 3 | data[13] << 5) & 0x07FF;
+	raw_channels[10] = (data[13] >> 6 | data[14] << 2 | data[15] << 10) & 0x07FF;
+	raw_channels[11] = (data[15] >> 1 | data[16] << 7) & 0x07FF;
+	raw_channels[12] = (data[16] >> 4 | data[17] << 4) & 0x07FF;
+	raw_channels[13] = (data[17] >> 7 | data[18] << 1 | data[19] << 9) & 0x07FF;
+	raw_channels[14] = (data[19] >> 2 | data[20] << 6) & 0x07FF;
+	raw_channels[15] = (data[20] >> 5 | data[21] << 3) & 0x07FF;
+
+	for (i = 0; i < CRSF_CHANNEL_COUNT; i++) {
+		raw_channels[i] = ConstrainF(raw_channels[i], CRSF_CHANNEL_VALUE_MIN, CRSF_CHANNEL_VALUE_MAX);
+		new_packet->channel_data.channels[i] = MapF((float)raw_channels[i], CRSF_CHANNEL_VALUE_MIN, CRSF_CHANNEL_VALUE_MAX,
+						       1000.0f, 2000.0f);
+	}
+
+	return true;
+}
+
+static bool ProcessLinkStatistics(const uint8_t *data, const uint32_t size, CrsfPacket_t *const new_packet)
+{
+	new_packet->message_type = CRSF_MESSAGE_TYPE_LINK_STATISTICS;
+
+	new_packet->link_statistics.uplink_rssi_1 = data[0];
+	new_packet->link_statistics.uplink_rssi_2  = data[1];
+	new_packet->link_statistics.uplink_link_quality = data[2];
+	new_packet->link_statistics.uplink_snr = data[3];
+	new_packet->link_statistics.active_antenna = data[4];
+	new_packet->link_statistics.rf_mode = data[5];
+	new_packet->link_statistics.uplink_tx_power = data[6];
+	new_packet->link_statistics.downlink_rssi = data[7];
+	new_packet->link_statistics.downlink_link_quality = data[8];
+	new_packet->link_statistics.downlink_snr = data[9];
+
+	return true;
+}
+
+static CrsfPacketDescriptor_t *FindCrsfDescriptor(const enum CRSF_PACKET_TYPE packet_type)
+{
+	uint32_t i;
+
+	for (i = 0; i < CRSF_PACKET_DESCRIPTOR_COUNT; i++) {
+		if (crsf_packet_descriptors[i].packet_type == packet_type) {
+			return (CrsfPacketDescriptor_t *)&crsf_packet_descriptors[i];
+		}
+	}
+
+	return NULL;
+}
+
+bool CrsfParser_LoadBuffer(const uint8_t *buffer, const uint32_t size)
+{
+	return QueueBuffer_AppendBuffer(&rx_queue, buffer, size);
+}
+
+uint32_t CrsfParser_FreeQueueSize(void)
+{
+	return RX_QUEUE_BUFFER_SIZE - QueueBuffer_Count(&rx_queue);
+}
+
+// 0xC8 [packet len] [packet type] [data] [crc]
+bool CrsfParser_TryParseCrsfPacket(CrsfPacket_t *const new_packet, CrsfParserStatistics_t *const parser_statistics)
+{
+	uint32_t buffer_count;
+	uint8_t working_byte;
+	uint8_t packet_size;
+	uint8_t packet_type;
+	bool valid_packet = false;
+
+	buffer_count = QueueBuffer_Count(&rx_queue);
+
+	// Iterate through the buffer to parse the message out
+	while ((working_index < buffer_count) && (buffer_count - working_index) >= working_segment_size) {
+		switch (parser_state) {
+		// Header
+		case PARSER_STATE_HEADER:
+			if (QueueBuffer_Get(&rx_queue, &working_byte)) {
+				if (working_byte == CRSF_HEADER) {
+					parser_state = PARSER_STATE_SIZE_TYPE;
+					working_segment_size = PACKET_SIZE_TYPE_SIZE;
+					working_index = 0;
+					buffer_count = QueueBuffer_Count(&rx_queue);
+					continue;
+
+				} else {
+					parser_statistics->disposed_bytes++;
+				}
+			}
+
+			working_index = 0;
+			working_segment_size = HEADER_SIZE;
+			break;
+
+		// Packet size type
+		case PARSER_STATE_SIZE_TYPE:
+			QueueBuffer_Peek(&rx_queue, working_index++, &packet_size);
+			QueueBuffer_Peek(&rx_queue, working_index++, &packet_type);
+
+			working_descriptor = FindCrsfDescriptor((enum CRSF_PACKET_TYPE)packet_type);
+
+			// If we know what this packet is...
+			if (working_descriptor != NULL) {
+				// Validate length
+				if (packet_size != working_descriptor->packet_size + PACKET_SIZE_TYPE_SIZE) {
+					parser_statistics->invalid_known_packet_sizes++;
+					parser_state = PARSER_STATE_HEADER;
+					working_segment_size = HEADER_SIZE;
+					working_index = 0;
+					buffer_count = QueueBuffer_Count(&rx_queue);
+					continue;
+				}
+
+				working_segment_size = working_descriptor->packet_size;
+
+			} else {
+				// We don't know what this packet is, so we'll let the parser continue
+				// just so that we can dequeue it in one shot
+				working_segment_size = packet_size + PACKET_SIZE_TYPE_SIZE;
+			}
+
+			parser_state = PARSER_STATE_PAYLOAD;
+			break;
+
+		// Full packet content
+		case PARSER_STATE_PAYLOAD:
+			working_index += working_segment_size;
+			working_segment_size = CRC_SIZE;
+			parser_state = PARSER_STATE_CRC;
+			break;
+
+		// CRC
+		case PARSER_STATE_CRC:
+			// Fetch the suspected packet as a contingous block of memory
+			QueueBuffer_PeekBuffer(&rx_queue, 0, process_buffer, working_index + CRC_SIZE);
+
+			// Verify checksum
+			if (Crc8Calc(process_buffer + PACKET_SIZE_SIZE, working_index - PACKET_SIZE_SIZE) == process_buffer[working_index]) {
+				if (working_descriptor != NULL) {
+					if (working_descriptor->processor != NULL) {
+						if (working_descriptor->processor(process_buffer + PACKET_SIZE_TYPE_SIZE, working_index - PACKET_SIZE_TYPE_SIZE,
+										  new_packet)) {
+							parser_statistics->crcs_valid_known_packets++;
+							valid_packet = true;
+						}
+					}
+
+				} else {
+					// No working_descriptor at this point means unknown packet
+					parser_statistics->crcs_valid_unknown_packets++;
+				}
+
+				// Remove the sucessfully processed data from the queue
+				QueueBuffer_Dequeue(&rx_queue, working_index + CRC_SIZE);
+
+			} else {
+				parser_statistics->crcs_invalid++;
+			}
+
+			working_index = 0;
+			working_segment_size = HEADER_SIZE;
+			parser_state = PARSER_STATE_HEADER;
+
+			if (valid_packet) {
+				return true;
+			}
+
+			break;
+		}
+
+		buffer_count = QueueBuffer_Count(&rx_queue);
+	}
+
+	return false;
+}